I'm stoked about send out my new promotional material to publishers. Last year I sent only postcards and no envelopes. This year I felt it was better to have an envelope to protect the artwork sample and also include SASE and comment cards. This way I can find out what the art directors thought of my work and hopefully get some email addresses. Here is where I took stock of everything! Can't wait to get all this stuff in. I also highly suggest you choose 5-10 clients to focus on and send work to. Make sure your samples are personable and memorable. Drawn + Drafted outlines all the Do's and Dont's on their youtube channel:

Here are the websites I used:moo.com : postcards, business cards, stickers, and cover letters. LOVE this site. Always amazing products. I highly suggest them. They offer samples packs for free. Also a few times a year they have 25% sales.

cardsandpockets.com : A6 and A7 envelopes. Best price and you can choose your quantity and colors.The return envelopes weren't my original color choice, but I saved $10 by choosing this amber yellow in clearance. :)

I ordered a custom letterhead from moo.com. I wanted a product that would make the artwork look great and I only trust moo.com for that. I uploaded my own design which had 3 4"x6" letters. I'll cut them out, so instead of having a folded letter I can keep it the same size as my 4"x6" postcard. Its best to make your material easy and fast to digest. Art Directors and Editors have limited time as it is.

vistaprints.com : comment cards. This will be my first time printing with Vista. Not sure what to expect. This item wasn't complicated in design, so I'm not too worried. This way Art Directors and Editors can just check a box and stick it in the mail with a SASE

Cover letter are optional. Often Art Directors wont have the time to read them, but it sometimes looks nice to have a resume and lovely letter quickly explaining why you want to work for them.